There has conventionally been known a solid-liquid separator for separating the liquid from a liquid-containing object to be treated, including organic sludge such as sewage disposal matters, waste water from a pig farm or the like, food waste crushed by a disposer, vegetable scraps ground into a mush, waste cow milk, waste tofu with added water, and other processed food, sludge obtained by biodegrading such organic sludge, and inorganic sludge such as plating wastes, ink wastes, pigment wastes, and paint wastes (see Japanese Patent Application Laid-open No. H5-228695 and Japanese Patent Application Laid-open No. 2004-357615, for example). The lower the concentration of the solid content of an object to be treated, fed to such solid-liquid separator, the lower the amount of solid content that can be separated from the object to be treated by the solid-liquid separator, resulting in inability to efficiently separate the object to be treated into a solid and liquid.
In dealing with this problem, there has been proposed a device for concentrating object to be treated, prior to separating the object to be treated into a solid and liquid by means of a solid-liquid separator (see Japanese Patent No. 4318735, for example). This type of conventional apparatus for concentrating object to be treated has a mixing tank that receives an object to be treated, containing liquid and a filter body disposed inside the mixing tank. The filter body has fixed plates disposed at intervals and movable plates disposed between adjacent fixed plates. The fixed plates and the movable plates each have a through-hole. Filtrate that is separated from the object to be treated flows into the filter body through filtrate inflow gaps between the fixed and movable plates.
This apparatus also has a cleaning member that presses and shoves the plurality of movable plates while in sliding contact with the outer circumferential surfaces of the plurality of fixed plates. Due to the presence of the cleaning member, the movable plates operate actively between the adjacent fixed plates, preventing clogging of the filtrate inflow gaps between the fixed and movable plates by the solid content of the object to be treated. In addition, the sliding contact between the cleaning member and the outer circumferential surfaces of the fixed plates can prevent the solid content from adhering to the periphery of the filter body. As a result, a large amount of filtrate separated from the object to be treated can be let flow into the filter body efficiently.
However, because the conventional apparatus for concentrating object to be treated is configured such that the cleaning member applies pressure to the movable plates and consequently shoves the movable plates, the cleaning member and the movable plates are brought into pressure-contact with each other by high pressure, possibly resulting in relatively early wear of the movable plates or the cleaning member.
Patent Literature 1: Japanese Patent Application Laid-open No. H5-228695 (JP H05-228695 A)
Patent Literature 2: Japanese Patent Application Laid-open No. 2004-357615 (JP 2004-357615)
Patent Literature 3: Japanese Patent No. 4318735 (JP 4318735 B)